This invention relates to a process for the production of flame-retardant polyurethane products by reacting salt-forming compounds in a polyol and/or a polyisocyanate, then reacting the polyol and polyisocyanate.
The production of polyurethane products is well known in the Arts and many types of flame-retardant chemicals have been used in the process. It is also known in the Arts that salts of phosphoric acid are useful as a flame-retardant, but when added to the polyurethane products, gthey take a large amount to do any good as a flame-retardant; therefore, they are not very useful. In the novel process of this invention, only a small amount of salts of phosphorus and-or halogen salts are necessary to produce a flame-retardant product because the molecules of the salts are small and very well distributed throughout the product. In the process of this invention, low-cost and readily available compounds are utilized and there is an improvement in the cost of the product, in the amount of flame retardant needed, and in the production of inexpensive flame-retardant compounds.
While not wishing to be bound by any theory of operation, it appears that there may also be some reaction of the salt-forming compounds with the polyol or polyisocyanate to give a much better and more stable distribution of salts, thereby proving flame-retardant properties. Any excess of basic salt-forming compounds may be used as a filler or may be a reactant in the process. It takes an amount at least 5 to 10 times more when the salt of phosphorus-containing compound is added to the reactive mixture to produce polyurethane products than it does when the salt is produced as outlined in this invention. The flame-retardant salt produced by the process of this invention is less expensive and at least equal to, or better than, the commercially available flame-retardant agents for polyurethane products in flame-retardant properties.